`BeanWrapperImpl` and `DirectFieldAccessor` are two
`ConfigurablePropertyAccessor` implementations with different features
set.

This commit harmonizes the two implementations to use a common base class
that delegates the actual property handling to the sub-classes:

* `BeanWrapperImpl`:  `PropertyDescriptor` and introspection utilities
* `DirectFieldAccessor`: reflection on `java.lang.Field`

Issues: SPR-12206 - SPR-12805